Aqueous concrete parting agents

ABSTRACT

A composition useful as a parting agent for concrete formwork is provided. The composition comprises water; a completely or predominantly unsaturated fatty alcohol containing 6 to 22 carbon atoms and with an iodine value of 40 to 200; and an alkyl or alkenyl oligoglycoside having an alkyl or alkenyl group containing 4 to 22 carbon atoms, a sugar unit containing 5 or 6 carbon atoms and a degree of oligomerization of 1 to 10. The parting agent is particularly storage-stable at low temperatures.

This is a National Stage Application of PCT/EP97/04870 filed Sep. 8,1997.

BACKGROUND OF THE INVENTION

1. Field of the invention

This invention relates to water-based concrete parting agents containingselected oils and emulsifiers, to a process for their production and tothe use of the mixtures of selected oils and emulsifiers for theproduction of water-based concrete parting agents.

2. Discussion of Related Art

Parting agents for concrete formwork and forms are known, for example,from the corresponding guideline of the “Concrete Technology” Committeeof the Deutscher Beton-Verein e.V., Wiesbaden (1980) and from H. Reul,Handbuch Bauchemie, Verlag für Chem. Industrie, Ziolkowsky AG, Augsburg,1991, pages 319 et seq. They are applied to the formwork before thefresh concrete is placed therein and are intended to reduce adhesionbetween concrete and formwork during stripping and to avoid damage tothe concrete surface and to the formwork. This is supposed to increasethe number of times the formwork material can be used.

The parting agents generally contain an oil component and variousadditives, for example rustproofing agents, antioxidants, anti-poreagents, preservatives, wetting agents, coupling agents and emulsifiers.The oil component may be selected from various classes of oils andmixtures thereof, for example mineral oils or white oils, waxes;triglycerides based on vegetable or animal oils or fats or fatderivatives. It is of particular advantage to use the concrete partingagents in the form of an aqueous emulsion. If they are to be used inthis form, the parting agents generally contain emulsifiers, such assoaps, ethoxylated fatty acids and ethoxylated alkylphenols or petroleumsulfonates in quantities of about 10 to 30% by weight, based on the oilcomponent. Normally, the parting agents are not delivered to the pointof use in the form of an emulsion, but rather in the form of aconcentrate which is diluted immediately before use.

The parting agents used today have various disadvantages. Mineral oilsor white oils as the oil component are not sufficiently biodegradable.Although triglycerides based on native oils, for example rapeseed oil,are readily biodegradable, they have relatively high viscositiesunfavorable for use. In addition, saponification of the oil by alkalineconstituents of the concrete can result in the precipitation of calciumsoaps, a phenomenon known as “sanding up”, which can cause adhesionproblems during further processing of the concrete. Fatty acid estersshow similar behavior. It has already been proposed to remedy thesituation by using distillation residues from the production of fattyalcohols, but unfortunately it has been found that these compounds canonly be partly used as the oil component, as described for example inDD-A5 290 439. In this case, the oil component used consists of 80 to90% by weight of mineral oil with an addition of 4 to 10% by weight of amixture of saturated and unsaturated wax esters containing 32 to 36carbon atoms, saturated and unsaturated fatty alcohols containing 24 to32 carbon atoms and hydrocarbon. In addition, the wax esters present inthe mixture can saponify which gives rise to the adhesion problemsdescribed above. WO 95/18704 (Henkel) describes concrete parting agentswhich contain optionally unsaturated fatty alcohols or Guerbet alcoholsas oil components and nonionic surfactants in the form of alkylene oxideadducts with suitable H-acid compounds as emulsifiers. European patentapplication EP-A 0 561 465 discloses mold release agents which containesters of sterically hindered polyhydric alcohols as compulsorycomponents. The use of monohydric alcohols is described as a way ofreducing the emulsifier content. British patent application GB-A1,294,038 describes a process for the production of concrete partingagents in which monohydric alcohols are used in combination withcationic surfactants.

The emulsifiers used for the production of aqueous emulsions are alsonot without their problems from the applicational point of view. Toproduce emulsions, it has hitherto been necessary to use relativelylarge quantities of emulsifier which, unfortunately, has an adverseeffect on the rainproof behavior of the parting agents. In addition, ifthe emulsifier content is high, re-emulsification can occur at theinterface with the alkaline cement, some of the parting agentpenetrating into the surface of the concrete. These residues of partingagent can subsequently lead to the above-mentioned problems affectingthe adhesion of paints or plasters.

Accordingly, there is a significant demand for concrete parting agentswhich are readily biodegradable and which have none of the disadvantagesof known compounds, such as high viscosity, surface deficiencies orsanding up. Another disadvantage is that, hitherto, known concreteparting agents could at best be assigned to Water Hazard Class 1. Therequirements which an environmentally compatible concrete parting agentshould satisfy are explained by way of example in RAL UZ 64 “Biologischschnell abbaubare Schmierstoffe und Schalöle” of June, 1991.

Accordingly, the problem addressed by the present invention was toprovide concrete parting agents having improved ecological compatibilitywhich would be distinguished by high resistance to saponification andwhich would form stable liquid emulsions, even at low temperatures. Inaddition, the viscosity of the emulsions would be so low that they couldbe sprayed without difficulty. Finally, the concrete parting agentsaccording to the invention would uniformly wet various formworkmaterials and would adhere firmly to them.

Other than in the operating examples, or where otherwise indicated, allnumbers expressing quantities of ingredients or reaction conditions usedherein are to be understood as modified in all instances by the term“about”.

DESCRIPTION OF THE INVENTION

The present invention relates to water-based concrete parting agentscontaining (a) unsaturated fatty alcohols and (b) alkyl and/or alkenyloligoglycosides.

It has surprisingly been found that the parting agents according to theinvention show improved rheology and storage stability compared with theprior art, particularly at low temperatures. The preparations areresistant to saponification, do not sand up, show good wetting behaviorand adhere even to the most diverse formwork materials. Anotheradvantage of the new parting agents is that they are ecologically safeand, accordingly, may be assigned to Water Hazard Class 0.

Unsaturated Fatty Alcohols

According to the invention, unsaturated fatty alcohols preferablycorresponding to formula (I):

R¹OH  (I)

in which R¹ is a completely or predominantly unsaturated hydrocarbonradical containing 6 to 22 and preferably 12 to 18 carbon atoms, areused as oil component (a). Typical examples are palmitoleyl alcohol,oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, linolyl alcohol,linolenyl alcohol, gadoleyl alcohol and erucyl alcohol and the technicalmixtures thereof obtained, for example in the high-pressurehydrogenation of technical fatty acid methyl ester fractions with thedouble bonds intact. Typical methyl ester mixtures which may be used asstarting materials for the production of the unsaturated fatty alcoholsare those derived from beef tallow, sunflower oil from old and newplants, rapeseed oil from old and new plants, linseed oil, peanut oiland the like. In addition, methyl esters based on predominantlysaturated fats and oils, such as palm oil, palm kernel oil and/orcoconut oil, may be used providing the products are then correspondinglyconcentrated, as described for example in DE-C2 43 38 974, DE-A1 43 35781, DE-A1 44 25 180 and DE-C1 44 22 858 (Henkel). The parting agentsaccording to the invention normally contain unsaturated fatty alcoholswhich have an iodine value in the range from 40 to 200, preferably inthe range from 50 to 150 and more preferably in the range from 70 to100. The unsaturated fatty alcohols are generally present in quantitiesof 10 to 50% by weight and preferably in quantities of 20 to 40% byweight, based on the parting agent.

Alkyl and/or alkenyl oligoglycosides

Alkyl and alkenyl oligoglycosides suitable for use as emulsifiercomponent (b) are known nonionic surfactants which correspond to formula(I):

R²O-[G]_(p)  (II)

where R¹ is an alkyl and/or alkenyl group containing 4 to 22 carbonatoms, G is a sugar unit containing 5 or 6 carbon atoms and p is anumber of 1 to 10. They may be obtained by the relevant methods ofpreparative organic chemistry. EP-A1 0 301 298 and WO 90/03977 are citedas representative of the extensive literature available on this subject.

The alkyl and/or alkenyl oligoglycosides may be derived from aldoses orketoses containing 5 or 6 carbon atoms, preferably glucose. Accordingly,the preferred alkyl and/or alkenyl oligoglycosides are alkyl and/oralkenyl oligoglucosides.

The index p in general formula (II) indicates the degree ofoligomerization (DP degree), i.e. the distribution of mono- andoligoglycosides, and is a number of 1 to 10. Whereas p in a givencompound must always be an integer and, above all, may assume a value of1 to 6, the value p for a certain alkyl oligoglycoside is ananalytically determined calculated quantity which is generally anon-whole number. Alkyl and/or alkenyl oligoglycosides having an averagedegree of oligomerization p of 1.1 to 3.0 are preferably used. Alkyland/or alkenyl oligoglycosides having a degree of oligomerization ofless than 1.7 and, more particularly, between 1.2 and 1.4 are preferredfrom the applicational point of view.

The alkyl or alkenyl group R² may be derived from primary alcoholscontaining 4 to 11 and preferably 8 to 10 carbon atoms. Typical examplesare butanol, caproic alcohol, caprylic alcohol, capric alcohol andundecyl alcohol and the technical mixtures thereof obtained, forexample, in the hydrogenation of technical fatty acid methyl esters orin the hydrogenation of aldehydes from Roelen's oxosynthesis. Alkyloligoglucosides having a chain length of C₈ to C₁₀ (DP=1 to 3), whichare obtained as first runnings in the separation of technical C₈₋₁₈coconut oil fatty alcohol by distillation and which may contain lessthan 6% by weight of C₁₂ alcohol as an impurity, and also alkyloligoglucosides based on technical C_(9/11) oxoalcohols (DP=1 to 3) arepreferred. In addition, the alkyl or alkenyl group R² may also bederived from primary alcohols containing 12 to 22 and preferably 12 to14 carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol,cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol,oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol,gadoleyl alcohol, behenyl alcohol, erucyl alcohol, brassidyl alcohol andtechnical mixtures thereof which may be obtained as described above.Alkyl oligoglucosides based on hydrogenated C_(12/14) coconut oil fattyalcohol having a DP of 1 to 3 are preferred. The alkyl and/or alkenyloligoglycosides are normally used in quantities of 0.2 to 5% by weightand preferably in quantities of 0.5 to 2% by weight, based on theparting agent, whereas the parting agents as such have a water contentof 50 to 90% by weight, more particularly from 50 to 80% by weight andpreferably from 60 to 70% by weight.

Auxiliaries and Additives

The parting agents according to the invention may contain small amountsof typical auxiliaries and additives such as, for example, corrosioninhibitors, antioxidants, anti-pore agents, preservatives, wettingagents, coupling agents and the like. The percentage content of theseauxiliaries and additives, based on the parting agent, is normallybetween 0.1 and 15% by weight and preferably between 0.1 and 5% byweight.

Production of the Parting Agents

The present invention also relates to a process for the production ofwater-based concrete parting agents in which a water-containing premixof the oil and the emulsifier is initially prepared with moderatestirring and is then homogenized in known manner, for example in anUltraturrax, a Supraton or any other high-pressure or toothed-ringhomogenizer, to form a fine-droplet emulsion.

Commercial Applications

The parting agents may be applied to the formwork surfaces in pure formor in the form of an emulsion by spray-coating, spread-coating orbrush-coating. The low-viscosity emulsions are so stable that they canbe sprayed without difficulty. Highly viscous pastes can also be appliedby knifing. Accordingly, the present invention also relates to the useof mixtures of (a) unsaturated fatty alcohols and (b) alkyl and/oralkenyl oligoglycosides for the production of concrete parting agentsused for steel, plastic or wooden formwork in concrete construction.

EXAMPLES

General production procedure. 700 kg of deionized water were heated to40° C. in a 2 m³ stirred tank reactor, followed by the addition of 10 kgof one of emulsifiers B1 to B3. 1.5 kg of the corrosion inhibitorTexamin® Ke 3161 (cocofatty acid monoethanolamide) were stirred into thetransparent, slightly viscous solution formed, a pH value of 10.5 beingautomatically established. Quantities of 300 kg of oils A1 and A2 werethen added with stirring and the premix was adjusted to pH 11.5 withdilute sodium hydroxide solution. After pretreatment in an Ultraturrax,the mixture was transferred to a high-pressure homogenizer where it wasprocessed to a fine-droplet emulsion.

The viscosity of the emulsions was determined by the Brookfield methodin an RVT viscosimeter (20° C., spindle 4, 10 r.p.m.). The stability ofthe emulsions was evaluated after storage for 4 weeks at 5° C. Theperformance properties of the emulsions are shown in Table 1. Mixture R1corresponds to the invention while mixtures R2 to R6 are intended forcomparison. It can be seen that low-viscosity concrete parting agentsresistant to low temperatures are only obtained using the combinationaccording to the invention of a selected oil component and emulsifier.

TABLE 1 Concrete parting agents (quantities in % by weight) R1 R2 R3 R4R5 R6 A1) Technical oleyl alcohol 30 — 30 30 — — (IV = 85) A2) Octyldodecanol — 30 — — 30 30 B1) Cocalkyl oligogluco-  1  1 — — — — side B2)Tallow alcohol + 5 EO — —  1 —  1 — B3) Sodium stearate — — —  1 —  1Water, preservative, corro- to 100 sion inhibitor Viscosity [mPas] 15150  200  170  170  200  Stability after storage Stable Sepa- Sepa-Sepa- Sepa- Sepa- rated rated rated rated rated Water Hazard Class  0  1 1  1  1  1

What is claimed is:
 1. A water-based concrete parting agent, comprising:(a) a fatty alcohol corresponding to the formula R¹OH  (I) wherein R¹ isa completely or predominantly unsaturated hydrogen radical containingfrom 6 to 22 carbon atoms and having an iodine value of from 40 to 200,said fatty alcohols present at from 10 to 50% by weight based on theparting agent; and (b) an alkyl or alkenyl oligoglycoside correspondingto the formula  R²O-[G]_(p)  (II) wherein R² is an alkyl or alkenylgroup containing 4 to 22 carbon atoms, G is a sugar unit containing 5 or6 carbon atoms and p is a number of from 1 to 10, said alkyl or alkenyloligoglycosides present at from 0.2 to 5% by weight based on the partingagent.
 2. The fatty alcohol (I) of claim 1 wherein R¹ contains from 12to 18 carbon atoms.
 3. The composition of claim 1 wherein the fattyalcohol (I) are present at from 20 to 40% by weight based on the partingagent.
 4. The alkyl or alkenyl oligoglycoside (II) of claim 1 wherein R²contains 4 to 11 carbon atoms.
 5. The alkyl or alkenyl oligoglycoside ofclaim 4 wherein R² contains 8 to 10 carbon atoms.
 6. The alkyl oralkenyl oligoglycoside (II) of claim 1 wherein R² contains 12 to 22carbon atoms.
 7. The alkyl or alkenyl oligoglycoside of claim 6 whereinR² contains 12 to 14 carbon atoms.
 8. The composition of claim 1 whereinthe alkyl or alkenyl oligoglycoside are present at from 0.5 to 2% byweight based on the parting agent.
 9. The composition of claim 1 whereinthe water is present at from 50 to 80% by weight of the parting agent.10. The composition of claim 9 wherein the water is present at from 60to 70% by weight of the parting agent.
 11. The composition of claim 1further comprising at least one auxiliary comprising corrosioninhibitors, antioxidants, anti-pore agents, preservatives, wettingagents, or coupling agents, said auxiliary being present at from 0.1 to15% by weight based on the parting agent.
 12. The composition of claim11 wherein at least on auxiliary is present at from 0.1 to 5% by weightbased on the parting agent.
 13. The composition of claim 1 furthercomprising from 50 to 90 percent water.
 14. A method for reducing theadhesion between formwork and fresh concrete, thereby facilitating theremoval of the formwork from cured concrete comprising: (a) applying acomposition of claim 1 to the surface of the formwork; (b) introducingfresh concrete into the formwork; (c) allowing the concrete to set orcure; and (d) removing the formwork from the cured concrete.
 15. Amethod of claim 14 wherein the composition of claim 1 is applied to theformwork as an emulsion by spray-coating, spread-coating orbrush-coating.
 16. The method of claim 14 wherein the composition ofclaim 1 is applied to the formwork as a paste.
 17. The method of claim14 wherein the formwork is steel, plastic or wooden.